空间等离子体

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Voyager 1 和 2的发现
Voyager 1 crossed the termination shock, September 23, 2005 Voyager 2 crossed the termination shock, August 30, 2007
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Termination of the Solar wind
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太阳风的发现
彗星中的双拖尾结构 1. Diffused one is caused by
solar radiation pressure; 2. The sharp one is caused by
solar wind.
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Solar Wind
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6
ຫໍສະໝຸດ Baidu
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8
Parker’s solar wind model (1958)
Total pressure balanced at the shock front
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注意如下关系式
T3 m knvvbvvbfvd3v
f
v
n v2
3 2
exp
v2 v2
mv2 T
2k
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定义： vt2h v 2 / 2
mv T
2
mvt2h
2k k
pnkT mt2 n hv1 2 v2
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理论预言的太阳风速率变化
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行星际中的磁场
Flux conservation
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太阳自转的影响
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实际的行星际磁场的传播
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太阳风如何被减速?
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Interstellar wind and background pressure
about 10-13Pa
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Solution: introducing a standing shock wave
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Voyager spacecraft
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Voyager mission
Voyager mission
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Solar wind at 1AU
Solar wind is fully ionized into electrons, protons, and He2+(3%);
Solar wind parameters measured by spacecraft near the Earth
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Interstellar wind
The majority of the interstellar gas and dust that we see was produced
by star death
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Solar Coronal Outflow
d r2nv0
dr
vddvrGr2Mn1mi ddpr
Fast wind
Slow wind
Velocity
500-800 km/s 250-400 km/s
Density
3x106 m-3
10x106 m-3
Proton temperature 2x105 K
4x104 K
Electron temperature 1.2x105
1.5x105 K
Magnetic field
从磁流体理论出发； 假设太阳大气层存在
一个加热源； 得到supersonic solar
wind.
9
Solar coronal outflow
假设日冕处于平衡态
即受重力场约束 连续性方程
v0
t
流体的运动方程 Vlasov equation 流体的能量方程
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Fluid momentum equation
2-10 nT
2-10 nT
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WIND and ACE mission
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Lagrangian point
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Quiz 4
1. 如果没有太阳风的直接测量，请问有什么 自然现象支持太阳风的存在？列举两种以 上。
2. 说说源自太阳赤道上和太阳极区的磁场有 什么差别，哪一种随日球层距离下降的快？
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Coronal Magnetic Field
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Interplanetary Magnetic Field
Introduction of Space Physics by M. G. Kivelson and C. T. Russell
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Parker Spiral magnetic field
Frozen-in Condition
E+V×B=0
1
3. Solar Wind and Interplanetary Magnetic Field
2
Outline:
太阳风的发现 太阳风的特性 太阳风的形成 太阳风传播的范围 1AU 处太阳风的测量 Coronal Magnetic field Interplanetary Magnetic Field Park Spiral and Heliospheric Current Sheet Corotating Interaction Region
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Summary
简单介绍了太阳风经典理论； 探讨了太阳风在Termination Shock的减速问
题; Parker Spiral行星际磁场,中性电流片,CIR；
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行星际中性电流片
The radial current in the circuit is on the order of 3×109 amperes. However, the maximum current density is 10-10A/m2
Image courtesy J. Jokipii, University of Arizona
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Heliospheric Current Sheet (HCS)
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Corotating Interaction Region
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Corotating Interaction Region shock
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MHD模拟的CIRs
http://www.physics.usyd.edu.au/~cairns/teaching/lecture11/node4.html